2. Adding the public key to the authorized key

In the first place, we need to upload the key to the remote machine:

user@host:~$ scp ~/.ssh/id_rsa.pub remoteuser@remotehost:~/

Now, the public key is uploaded, let's add it to the authorized keys. To do so, we are going to connect to remotehost as remoteuser and add the key at the end of file ~/.ssh/authorized_keys and delete it once added: